This invention relates to a circuit arrangement comprising
a power amplifier stage located on a forward gain path arranged between a signal input and a signal output, PA1 a feedback path, connecting the signal output to the signal input, and comprising an extraction stage for extracting part of a signal from the output of the power amplifier stage to the feedback path, and comprising a feedback function stage, PA1 a re-combining stage for re-combining a feedback signal from the output of the feedback path with an external input signal, an output of the recombining stage being coupled to the signal input of the power amplifier stage, PA1 a first gain control element in the forward gain path, PA1 a second gain control element in the feedback path, and PA1 a control circuit which varies the first and second gain control elements inversely, so that the product of their gain factors remains constant, in essence.
From European Patent Application 0 638 994, to whose overall disclosure content is expressly referred hereby, is known such a circuit arrangement of the type disclosed in the first claim. This circuit arrangement is to achieve a linearization of the transmission characteristic of the power amplifier stage. Since the gain factors of the gain control elements are varied inversely, so that their product remains substantially constant, there is additionally achieved that the feedback loop (formed by forward gain path, feedback path and re-combining stage) formed by the circuit arrangement is also operated with different powers transmitted via the power amplifier stage with constant signal levels on the signal input and is thus capable of operating at a signal level to which it is optimally designed.